Environmental Engineering Reference
In-Depth Information
-2 CO
2
2 C
2
H
6
O
Ethanol
- 2 CO
2
, -H
2
O
C
4
H
10
O
1-Butanol or diethyl ether
- 2 CO
2
, -2 H
2
O
C
4
H
8
O
Butene
Glucose
C
6
H
12
O
6
- CO
2
, -H
2
O
C
5
H
10
O
3
C
3
H
6
O + C
2
H
4
O
2
Ethyl lactate or
acetone and acetic acid
- CO
2
, -2 H
2
O
C
5
H
8
O
2
γ
-Valerolactone
- 3 H
2
O
C
6
H
6
O
3
Hydroxymethylfurfural
FIGURE 18.3
Possible structures upon release of three or more O atoms from glucose.
Example 18.2 Conversion of xylose
Write down the chemical equation for the fermentation of xylose to ethanol and for
the dehydration of xylose to furfural, and determine the atom efficiencies of these
reactions. Based on this information, which process is more attractive for biofuel
purposes? Which information are you lacking?
Solution
Aerobic fermentation of xylose:
C
5
H
10
O
5
+2O
2
!
C
2
H
5
OH+ 3CO
2
+2H
2
O
The atom efficiency for ethanol production thus is
46
150 + 2
32
100
=21
%
%
Chemical dehydration of xylose:
C
5
H
10
O
5
!
C
5
H
4
O
2
+3H
2
O
The atom efficiency for furfural production is
96
150
100
=64
%
%
Based on this information, furfural production seems most attractive for biofuel
production because of its higher atom efficiency.
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